2019-05-24_PERMIT FILE - M2019027 (2)

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C-8 Initial pit development will encompass the establishment of a pit perimeter berm that will serve both as a safety feature to delineate the full extent of excavation and as a diversion feature to mitigate surface water run-on potential(into the pit). It is anticipated that development of the main mine pit will commence at the west end of the pit with a nominal 10%decline ramp. The primary pit (approximately 375-ft. long x 235-ft. wide) mined tonnage will be utilized to replenish ROM 1 stockpile(feed source to wet plant). An initial 12-ft. bench(cut)will be mined by front-end loader and/or hydraulic excavator loading to articulated haul truck units. Pit sidewalls will be maintained at a nominal 3H:1 V slope (consistent with the natural angle of repose of the exposed sand material). Full pit development will follow, to include removal of a second 12- to 13- ft. bench (cut) to achieve the full pit depth objective of approximately 25 ft. The main mine pit will be mined to a nominal pit floor elevation roughly equivalent to that of the adjacent fines recovery pit. The sand resource is an unconsolidated, eolian sand deposit that is anticipated to be relatively consistent in terms of size distribution and quality characteristics across the entirety of the planned pit area. Due to the unconsolidated and free-flowing nature of the material, blasting is neither required, nor proposed. All material extraction will be accomplished via direct excavation utilizing either a hydraulic excavator or front-end loader(s). While it is indeterminate at this time whether or not the west pit extension (the surface of which is to be initially occupied by the growth medium stockpile TS-IA) will be mined, CSC may elect to do so if additional production tonnage is desired. In the event this were to occur, the growth medium stockpile TS-1 A would first be relocated to an area within the mined-out pit in order to allow access to the underlying sand resource. The selected location for the relocated growth medium stockpile, likely at the east end of the pit floor, would be designated TS-113. If the west pit extension zone is not mined, growth medium stockpile TS-1A will remain in-place until site reclamation is undertaken. Alternatively (or in addition to the potential west pit extension), incremental tonnage may be recovered through a deepening of the main mine pit, if warranted. Keenesburg Project—Limited Impact 110 Application_May 24,2019